Help with applying the same texture to different shaped objects
There's a solution that doesn't even need any unwrap, but of course it only works if you don't care about not having UVs:
Use the Image Texture's Box option instead of Flat. This way the texture is projected on each side of the object. The Blend option allows you to have smooth transitions between the X, Y and Z projections. A good thing is probably to also use an empty as Object in the Texture Coordinate. Then use the Mapping values to correctly scale and place the texture.
To switch from a plank to another, move the first plank away and bring the second one to the exact same location with some ShiftS, or even simply AltG, or move the empty instead of the plank.